Absorption of High‐Energy Gamma Rays by Interactions with Extragalactic Starlight Photons at High Redshifts and the High‐Energy Gamma‐Ray Background

Abstract

In this paper, we extend previous work on the absorption of high-energy c-rays in intergalactic space by calculating the absorption of 10500 GeV c-rays at high redshifts. This calculation requires the determination of the high-redshift evolution of the intergalactic starlight photon eld, including its spectral energy distribution out to frequencies beyond the Lyman limit. To estimate this evolution, we have followed a recent analysis by Fall, Charlot, & Pei, which reproduces the redshift dependence of the starlight background emissivity obtained by the Canada-France Redshift Survey group.